Experimental branch is available for everyone !!!
If you want to test future updates in advance, you can do so now on Steam by clicking:
On the gear icon in the top right corner of your library
Then on Properties
Then Beta,
And then selecting the "Experimental" version.
Please note that the experimental version is not the final version of the game and all mechanics may change, potentially corrupting your game or ruining the economy of your save.
PLEASE DO A COPY OF YOUR GAME IF YOU PLAY EXPERIMENTAL VERSION
It's already available on Steam, every bug or suggestion of the experimental version NEED to be on the steam discussion:
https://steamcommunity.com/app/3498270/discussions/0/588433186648779119/
This will allow us to ensure the updates are suitable for more people and to get much more feedback from you before the update is actually released ;D